Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
h, w = map(int, input().split())
s = []
sharp = 0
for i in range(h):
	t = input()
	sharp += t.count("#")
	s.append(t)

queue = deque([[0,0]])

visited = [[-1 for i in range(w)] for j in range(h)]
visited[0][0] = 0
d = [(1,0),(0,1),(-1,0),(0,-1)]
while queue:
	i, j = queue.popleft()
	for n, m in d:
		x = i+n
		y = j+m
		if x < 0 or x >= h or y < 0 or y >= w or s[x][y] == "#" or visited[x][y] != -1:
			continue
		visited[x][y] = visited[i][j] + 1
		queue.append([x,y])
if visited[h-1][w-1] == -1:
	print (-1)
else:
	ans = h*w-visited[h-1][w-1]-1-sharp
	print (ans)